So if the numbers are correct the weight savings is 4 ounces rather than 10. If you only compare the weight of the belt vs. the weight of the chain then the weight reduction approaches 8/10 ounces, however you have to account for the weight of the Gates sprockets.

I had been giving some thought to the Gates belt drive but do not see that it has any real advantage over the tried, try and efficient chain drive system for us. Especially when you look at the cost of the system and replacement costs. I think the jury is still out on what the Gates system is doing to bottom bearing wear.

Hmmm. They're probably comparing against what the AVERAGE tandem runs, which, considering the percentage of entry level vs performance tandems, would be a generic 1/8 or 3/32 chain.

But you're right in that they ought to compare against a top of the line 10 or 11 speed chain. After all, the guy who is predisposed to go Gates is probably already a weight weenie and running the lightest gear he can. Like your 11 speed Campy Record.

__________________BICYCLE - [[I]bahy-si-kuhl] - Noun :> A medical device used to correct the common geriatric condition of OFS, (Old, Fat & Slow), in a manner that does not induce brain-decaying boredom like walking or running.

I agree. Field repair is also an issue since a special tool is required to remount a belt if it comes off.

The only tool you need to remount a belt is what ever tool you need to loosen the eccentric as you are not supposed to force it on like you can a chain. We have had ours for about 4000 miles without any issues whatsoever. It got noisy once after riding in very dusty gravel construction area and a squirt form the water bottle solved the noise. As we travel with our tandem often it has been on and off the bike a number of times and I simply coil it up for travel like a new comes from Gates. I don't think there are any great mechanical advantage but we sure like no dirty chain to deal with.

Yes, the weight savings appear to be only in the belt. I didn't weight ours, but the Gates pulleys did not feel lighter than sprokets.
We have almost 10,000 miles on our belt with no issues whatsoever, but then how often is a timing chain replaced anyway. It is nice to be able to lay the bike down in the back of the Durango on the left side. Plus their is no chain type lash between cranks, both cranks feel directly connected. I would guess the belt is not quite as efficient as a chain since the belt is stiff.

No greasy/oily stuff on our tandem chains.
We've used the hot wax (canning wax/paraffin) method for the past 35+ years.
Have ridden a tandem porototype with the belt years back; was not overly impre$$ed.
Just our input/experience.
Want to save weight? Carry one less waterbottle!
Rudy and Kay/zonatandem

Actually, there is no Super Record chain. The Campy 11-speed chains are Chorus and Record.

Quote:

Originally Posted by BikeForums.net

It is nice to be able to lay the bike down in the back of the Durango on the left side.

I agree that the biggest advantage of a sync belt on a tandem is the cleanliness. A sync chain is long and exposed, and makes the tandem a constant threat to get oil stains on anything it gets near. That feeling of wariness and dread with the tandem is diminished significantly with the belt drive, as the right drivetrain is shorter, less exposed, and the left side of the tandem is completely safe.

IIRC the weight was compared to a very heavy KMC chain that was standard on CoMmotion tandems.

Correct, I think this was discussed a couple of years ago, and this was the best answer. Gates originally designed the belt to work with a Co-Motion; the upgrade that Co-Motion offered was from a pair of FSA timing rings and KMC 8-speed chain to the belt setup. Co-Motion therefore published the weight difference between these two setups, which is completely justified. If Gates are now using this weight difference in their advertising without saying what the setup used for comparison is, then it could be a bit misleading.

When I built up our Comotion Speedster (size Small), I was surprised that I needed more than one chain's length to meet the length requirement for the timing chain only. Seemed like almost two chains worth, but not sure - it was long ago. Different bikes will have different lengths of timing chain, but I remember being disappointed from the extra weight that I did not account for. Thinking of riding the tandem again, and trying to lighten up, so Gates drive might do it for me.

I'm doubtful that the Gates chainrings weigh 190g vs 70g for aluminum rings. With my Centertrack (CDX) setup, the total weight (rings + belt) is around 200g. This saves about 200g over a conventional timing chain setup.

When the TandemGeek tested the older Gates belt (non-CDX), he found that it was 170g lighter than the lightweight daVinci chain setup:

The CDX rings are lighter, and should be as light or lighter than most aluminum rings. Co-Motion claims a weight savings of 283g but this is a bit optimistic. It's reasonable to save 200-230g.

The incremental cost is not that big. Precision Tandem sells the CDX belt for $100. A high-quality chain from Campy or Shimano is $50-80 each (10 or 11sp). You need two for the timing chain so the cost is basically the same as a Gates belt. Plus the Gates will easily last 2-4 times longer than a chain.

Precision sells a complete CDX system for $265. A conventional timing chain system is around $160 depending on your choice of rings. So the Gates belt drive will save you at least 200g for a premium of about $100. It's also quieter, cleaner, and needs less maintenance. How many bike upgrades provide the same amount of benefit for $100?

I recently replaced our timing chain and chain rings with the Gates CDX carbon drive belt system.
The old 9 speed SRAM chain weighed 405g, and the old chainrings weighed 85g for the pair.
The new belt is 110 g, new CDX rings are 155g for the pair. So the 225g difference = 8 oz lighter. But if you are as cautious as I am, a spare belt adds 4 oz back.

I'm not aware of any tandem team being stranded from a broken CDX belt. Belts have been around for awhile and are commonly used on cars and motorcycles. But it doesn't hurt to carry a spare belt if you're touring.

I never take a spare belt when touring. It'd be easy to buy a pair of rings and a couple chains at a bike shop in the extremely unlikely event that the belt failed. And a tandem can always get to a bike shop!

To be clear, the 405 grams I posted was for enough chain to make a complete timing chain, constructed out of portions of 2 SRAM 9 speed chains, spanning the same length as was replaced with a 250 tooth Gates belt

A typical timing chain has between 152 and 162 links. I wonder how a 116 link chain would reach around both cranks and join up, even if 243g.

On my tandem 1 and a bit KMC X11SL chains would weigh 339.3 grams.

Most timing chains would weight 340-360g, which is around 240g heavier than the CDX belt. This means that the whole Gates system is more than 200g than the conventional timing chain.

The X11Sl retails for $90, but is often on sale for $70. Since you need to buy a pair, the KMC timing chain will cost $140. I suppose that you can keep the extra links for a 2nd set, but it seems like a hassle for no particular benefit.

The X11Sl retails for $90, but is often on sale for $70. Since you need to buy a pair, the KMC timing chain will cost $140.

I have never paid anywhere near that. You can buy them on E-bay for $40 right now.
I only use them on my single bike. Since the tandem is 10 speed I use X10SL on the rear and plain X10 for the timing chain. A few extra grams doesn't matter to me. I only use the X10SL on the rear because I feel it shifts better.

Generally consistent with what I found when I converted: the "sprockets" are heavier for the Gates system but the belt is *much* lighter giving a lower overall number. Don't care to argue about the magnitude of how much lighter personally. I find a number of other benefits to the belt system in addition to the lower weight.

Yes the bike will ride the same either way. Like most bike bling you will very likely not be able to tell the difference in how the bike rides. But it WILL look cool and make you feel way better riding the bike. And, not speaking for all tandem teams here, but if I cannot look good riding the bike at least I want my bike to look good with me riding it